The present invention claims priority from Japanese Patent Application No.9-216739 filed Aug. 11, 1997, which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a magnetic disk device for contact recording/reproducing and, particularly, to a mechanism for supporting a magnetic head slider thereof
2. Description of Related Art
The recording density of a magnetic disk device has been increased on account of mainly the improvement of the magnetic characteristics of a magnetic head and a recording medium and the reduction of a distance between a gap of a magnetic head and a surface of a magnetic layer of a recording medium, that is, the so-called magnetic spacing. Nowadays, the magnetic spacing is in the order of 40 to 50 nm dependent upon the roughness of an air bearing surface of a flying head slider, a protection film on a magnetic recording medium, lubrication films and a surface roughness of a recording medium. However, in order to realize a recording density as high as 10.about.20 Gb per square inch or more, the magnetic spacing must be 15 nm or smaller. As one of means for realizing such small magnetic spacing, a slide type magnetic disk device for performing recording/reproducing operation while a magnetic head is in slide contact with a surface of a recording medium has been developed (cf. for example, H. Hamilton, Journal of Magnetic Society of Japan, Vol. 15, Supplement No. S2 (1991) 483 and Japanese Patent Application Disclosure Hei 5-508808). With such slide type magnetic disk device, it is possible to drastically reduce the distance between a magnetic head and a surface of a magnetic layer of a recording medium.
FIG. 1 is a cross sectional view schematically showing a basic construction of the conventional slide type magnetic disk device. In FIG. 1, the slide type magnetic disk device is constructed with a slide type magnetic head 7 for performing a recording/reproducing operation with respect to a magnetic recording medium 101, a magnetic head slider 1 on which the slide type magnetic head is mounted and a suspension leaf spring 106 for supporting the magnetic head slider and urging it to the magnetic recording medium. The suspension leaf spring 106 is connected through a positioning actuator arm 24 to a positioning actuator 102 for moving the slide type magnetic head 7 on the magnetic recording medium 101. The suspension leaf spring 106 presses the magnetic head slider 1 against the magnetic recording medium 102 by utilizing the elasticity of the whole leaf spring.
FIG. 2 is a disassembled perspective view of the magnetic head slider 1 and the suspension leaf spring 106, a portion of which is shown by cross section. In FIG. 2, a yoke 111 is buried in a contact pad 8 formed in a top end portion of the magnetic head 7 and performs a recording/reproducing operation with respect to the magnetic recording medium by slide contact therewith. An electric print cable 31 is directly formed on the suspension leaf spring 106.
Although the suspension leaf spring 106 in the above mentioned conventional magnetic disk device is a single leaf spring, a slide type magnetic disk device equipped with a gimbal mechanism has been also developed in order to improve the tracking of the suspension spring with respect to the magnetic recording medium. FIG. 3 is a cross section showing a basic construction of an example of the latter suspension spring, in which components similar to those shown in FIG. 1 are depicted by the same reference numerals, respectively. In FIG. 3, a magnetic head slider supporting mechanism is constructed with a gimbal 121 for supporting a magnetic head slider 1 and a beam suspension 6 for supporting the gimbal and applying a load to a magnetic head 7.
Incidentally, when the magnetic head seeks on the magnetic recording medium, the magnetic head slider supporting mechanism is required to have high rigidity in a width direction of a recording track and have strength enough to withstand frictional force and viscose fluid force generated between the magnetic head slider and a lubricant film on the surface of the magnetic recording medium. Further, in order to make it possible for the magnetic head slider to track the magnetic recording medium in contact therewith or with a minute distance therebetween, the magnetic head slider is required to have a flexibility suitable to allow a rolling (rotary movement about an axis parallel to a running direction of the magnetic recording medium) and a pitching (rotary movement about an axis orthogonal to the running direction of the magnetic recording medium and parallel to a surface of the magnetic recording medium) of the magnetic slider.
If, among the two contradictory requirements, the flexibility of the magnetic head slider is made prior to the other, the rigidity for the in-plane vibration mode and the primary and secondary torsional vibration modes of the whole suspension is lowered. Therefore, the vibration amplitude is increased and resonance frequencies of the respective modes are lowered. Since these vibration frequencies exist outside the controllable range, these frequencies appear as an off-track of the recording/reproducing head with respect to data track recorded on the recording medium. Therefore, it is impossible to record/reproduce the data until the vibrations in these modes excited by an access operation are sufficiently attenuated, so that a high speed access becomes impossible. Further, since vibration due to external disturbance other than the access operation resides as an off-track in a track follow state, a high speed and high density recording/reproducing becomes impossible.
On the other hand, if the rigidity of the magnetic head slider is made prior to the flexibility thereof, the tracking characteristics of the magnetic head slider with respect to the magnetic recording medium is degraded. Therefore, the sliding characteristics of the contact face of the magnetic head slider with respect to the surface of the magnetic recording medium becomes unstable and abrasion is enhanced, resulting in that the HDI reliability is lowered and the error rate is degraded by a variation of the recording/reproducing signal intensity due to an increase of jumping of the magnetic head slider.